1. Field of the Invention
The present invention generally relates to an apparatus that produces gaseous vapor baffling.
2. Description of the Prior Art
Many of today's ships and surface vessels operate at speeds exceeding 30 knots. However, when ships and vessels travel at these speeds, acoustic noise is generated from bubbly wakes, noisy propulsion devices and appendages. If these ships or vessels have sonar arrays attached to their hulls, or are towing sonar arrays in their wakes, the operation of such sonar arrays are adversely affected by the aforementioned acoustic noise. Specifically, the turbulent flow of water over the fairing structure of the sonar array generates pressure fluctuations on the fairing structure. Both turbulent boundary layers and turbulent wakes contribute to this type of structural excitation. The sonar array can experience these pressure fluctuations directly when the flow over the sonar array is turbulent, or indirectly when these pressure fluctuations propagate through the fairing structure or the support strut supporting the sonar array and into the sonar array. Fluctuating cavitation bubbles and collapsing vapor bubbles also produce significant noise that propagates through support struts and other structures connected to the sonar array. Noise generated by the vessel propulsion system also generates a significant amount of acoustic noise. Blade tonals, cavitation bubbles, and entrained air all generate noise that propagates through the environment to the sonar array. Similarly, breaking bow-waves, hull slapping, ship machinery noise, and other ship related noise sources also can affect operation of the sonar array. Furthermore, a mechanical path from the noise source through the structure supporting the sonar array exacerbates the acoustic noise problem. Thus, the ability of these sonar arrays to detect obstacles, marine mammals, debris and mines is significantly degraded as a result of the acoustic noise interference.
The prior art reveals several sonar systems, sonar support systems and particular design configurations for water craft. Soderman U.S. Pat. No. 3,910,215 discloses a hydrofoil that is pivotally mounted to a vehicle to allow the hydrofoil to absorb shocks. Dewitt U.S. Pat. No. 3,915,106 discloses a hydrofoil incorporating a ventilation system for introducing air into the flow over the hydrofoil. Andersen U.S. Pat. No. 4,745,584 discloses a transducer array mounted in a fairing. Archibald U.S. Pat. No. 5,008,863 discloses a sonar support system that has a sonar array mounted in a hydrofoil that is supported on a strut that is coupled to a ship. Bobst U.S. Pat. No. 5,524,568 discloses the use of a ventilation system to inject air at a plurality of spaced-apart aperture arrays formed in the hull of a boat. Seaman et al. U.S. Pat. No. 6,008,296 discloses a transducer array mounted in a hydrofoil-shaped fairing. Nesbitt U.S. Pat. No. 6,095,076 discloses the use of flexible struts to support hydrofoils. Lang U.S. Pat. No. 6,167,829 discloses the injection of air to form a gas cavity over a marine vehicle component such as a hydrofoil. Air is injected at either end of the component. None of these prior art patents disclose, teach or suggest the apparatus of the present invention which employs a novel technique to reduce acoustic noise interference with undersea sonar arrays or systems that are joined or attached to the underside of a ship or vessel.